LONDON – Roger Federer has set his sights on more indoor glory after the Swiss great booked his place in the semifinals of the ATP Tour Finals at London’s O2 Arena.Federer became the first player to qualify for the last four at this year’s season-ending event thanks to a 6-4, 7-6 (7/5) victory over Spain’s David Ferrer on Thursday and the world No 2 looks in ominous form as he eyes a seventh Tour Finals title.Few players have ever been more at home on the indoor courts than Federer and once again he is thriving under the domed roof of the O2 Arena in south-east London, where he has won the Tour Finals for the last two years.In total, Federer has won 20 indoor titles during his illustrious career and the 31-year-old admits he is more comfortable than most playing under roofs after growing up on covered tennis courts."Indoors I’ve been very successful over the years. Probably won the most titles indoors, maybe more than all the other guys combined,” Federer said."The margins actually are smaller indoors normally because a guy can really get hot, can serve well."But I think indoors is a natural surface for me. So is clay actually, because those were the two surfaces I grew up on.Federer’s win over Ferrer clinched his 10th semifinal berth in his last 11 appearances at the season-ending event, leaving him with a dead rubber to come against Juan Martin del Potro on Saturday.But the 17-time Grand Slam champion has no intention of taking it easy against the Argentine, who stunned Federer in the final of the Basle Open last month.